Hi Alexandra,
I'm late to the wedding (with limited experience as participant or guest and none as
caller) but this info can be filed away.
Android (I've no idea what platform you are using for playback) has a dearth of great
apps for tunes but my default happens to include an easy to use feature to alter the
playback tempo in 5% increments. So, if your recorded tunes are in a suitable file format,
this could be used to effectively rein in, or goose, the horses.
The app is Pulsar. I use the free version.
Cheers,
Ken Panton
Ottawa